The present invention relates to the synthesis of dimer alkaloid compounds, particularly those of the Catharantus (Vinca) family, such as vinblastine, vincristine and leurosidine, sometimes referred to hereinafter as the target compounds or the target dimer alkaloid compounds.
The dimeric alkaloids of present interest have remarkable anti-viral, anti-tumor and anti-leukemic properties. In the past, these alkaloids were isolated from the Catharantus species, particularly C. roseus, in small quantities. More recently, progress has been made in the synthesis of these compounds (U.S. Pat. Nos. 4,144,237 and 4,279,817 to James P. Kutney, and parent application U.S. Ser. No. 07/011,810). Unfortunately, these prior art methods also yielded small quantities of the target compounds. The present invention overcomes the difficulties encountered in the prior art insofar as it yields dramatically increased quantities of the target dimer alkaloid compounds.